<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <input id="input" type="text" style="width: 300px;">
    <div id="content" style="color: blue; margin-top: 10px;"></div>
    <script>
        window.onload = () => {
            const data = { value: ''}

            const proxyObj = new Proxy(data, {
                set: (target, key, value) => {
                    if (key === 'value') {
                        const content = document.getElementById('content')
                        content.innerHTML = value
                    }
                }
            })
            
            const input = document.getElementById('input')
            input.addEventListener('input', (e)=> {
                proxyObj.value = input.value
            })
        }
    </script>
</body>
</html>